Herpes simplex viruses (HSV) remain a major health problem primarily due to their potential to invade neuronal tissue, to establish latent infections, and their possible role as cofactors in certain cancers. The studies proposed are divided between two specific aims that represent an extension of our current research efforts directed towards the characterization of HSV glycoproteins and defining the functional role they play in virus-cell/host interactions. The first specific aim focuses on the HSV-2 glycoprotein designated, gG-2. The rationale for studies on gG-2 relate to its unique properties relative to its HSV-1 homolog as well as being the only HSV glycoprotein to undergo a cleavage event during its processing. The overall objective of the studies proposed in the first specific aim will be to identify the role gG-2 plays in virus replication and assembly, pathogenesis, and the induction of the immune response. Experiments are proposed to use a gG-2 null virus as well as a gG-2 cleavage-minus virus. These mutant viruses will serve as key reagents to determine the role gG-2 plays in initiating infection within various cell cultures. Particular emphasis will be placed on the use of cells of neuronal origin. The second aspect of specific aim one concerns identifying the role gG-2 may play in the pathogenesis of the virus infection of the host. Mice will be used as the animal model. The pathogenicity of the wild type virus will be compared to the gG-2-null virus and the gG-2 cleavage-minus virus. Finally, the role gG-2 plays in the induction of the cell-mediated immune response will be addressed. Initial studies will focus on identifying the effectiveness of gG-2 serving as a target for cytotoxic T cells and identifying the epitopes involved. The second specific aim will focus on the interaction of HSV glycoproteins with tegument proteins of the virus particle. It is our hypothesis that the interaction between virus glycoproteins and the matrix-like (tegument) proteins are likely to serve important roles in the virus assembly process. However, information regarding the identification of HSV proteins that serve as matrix-like proteins and the glycoproteins with which they interact is quite limited. Initially, our studies will focus on specific interactions that may occur between gD and a major tegument protein designated VP16. In addition, studies are proposed to identify the potential interactions of other glycoproteins and tegument proteins. Once specific interactions between certain glycoproteins and tegument proteins are identified, the peptide domains responsible for these interactions will be addressed using synthetic peptides to inhibit the protein-protein interaction as well as deletion mutants and site-directed mutagenesis. The various mutants will also be used to define how glycoproteins and tegument proteins interact with regard to the virus assembly process.